Method and apparatus for applying armor tape

ABSTRACT

Stiff armor strip for a cable core is pretwisted between two pairs of heavy rolls on the armoring machine and bent sharply at the downstream roll. Double bending of the strip is avoided.

United States Patent 1191 Burr May 21, 1974 ['54] METHOD AND APPARATUS FOR APPLYING ARMOR TAPE [56] References Cited [75] Inventor: Harvey Burr, Bronxville, NY, UNITED STATES PATENTS 3,295,310. 1/1967 Beighley 57/145 [73] mPa" Nafw 3,388,541 6/1968 Biagini or 1 3,717,987 2/1973 Gilmore et a1 57/9 [22] Filed: Aug. 14,1972 Ch W h Primary Examinerarles Lan am [211 App! 280637 Assistant Examiner-Joseph A. Walkonski I v Attorney, Agent, or Firm-Victor F. Volk [52] US. Cl 57/9, 29/624, 57/55,

. 57/161, 174/1/08 [57] ABSTRACT [51] Int. Cl H0lb 13/26 l-iOlb 13 08 Field of Search 156/417 49, 50 56; St1ff armor strip for a cable core 15 pretw1sted between 145, 161,166; 174/102 R, 102 C, 102 D, 103, 105R, 106 'R, 106 D, 108

two pairs of heavy rolls on the armoring machine and bent sharply at the downstream roll. Double bending of the strip is avoided.

I 12 Claims, 6 Drawing Figures PATENTEBHAY g 1 m4 SHEEI 1 1F 3 METHOD AND APPARATUS FOR APPLYING ARMOR TAPE BACKGROUND OF THE INVENTION This invention has application wherever a stiff or springy strip is helically appliedaround an elongated core. An applicationthat has particular commercial significancexresides in the. armoring of flexible cable or hose and particularly in thea'rmoring of electrical cable withflat steel armor such, for an example, as that describedin application'ofBarone et al. entitled Making FlatCopper-Clad Steel Wire, Ser. No. 242,173, assigned to the assignees of the present invention. The word strip as used in: this application refers to a strand'of non-circular. section. This is practically distinguishable from circular strand in that, when it is wrapped around a core, any. twisting-of the strand beyond that required by the helix of the wrap (or below that required for the helix); will be immediately evidenced as an unevennessin the surface'of-the wrapped core, and, where theuturns. are. closely abutted, in gaps in the coverage'of the core surface: When stiff armor is wrapped around-aflexible coreit presents a problem of bird-caging when the. core is bent or flexed. This is particularly troublesome where thearmoris applied in a large plurality of endsand a long lay or pitch, since once they havebird-cagedthe ends may.overlap rather than lay side by side when the core is straightened or the flexing reversedi Although. thisproblem-exists with round armor it is more accentuated for strip, since the turns, once theyihave overlapped, tend to remain that way. Another seriousproblem with stiff armor, particularly if it is somewhatspr'ingy, as is usually the case with steeL'results from the need to make splices, and to cut the armor at connections. If long sections of armor either round or strip, unwind during splicing, it maybe difficult or impossible to rewind them properly under field conditions. A further problem that is not confronted with round'armor butmay be quite serious with strip resides in the tendency of one edge of the strips to rise while the other edge digs in. This may not only result to damage to the surface of the core and to loss of complete coverage, but it increases the cable diameter and reduces the surface smoothnessand ease of pulling. Where an outer covering'is applied over the armor, the upturned edges of the strip will tend to cut through it, make it more difficult to apply, and require an additional quantity of the outer covering. Means of preforming flat wire has been suggested similar to known means for round wire and involving a bending of the wire, followed by straightening, wherein a strain is retained in the wire-disposing it tothe desired configuration. l have found that known types of preformers not only require a severe and unnecessary-working of the strip, but did not, in practice, result in a smooth and easily handled application of armor.

SUMMARY In my method of helically applying at least one armor strip, and preferably in excess of six strips, to an elongated core I comprise the stepsof continuously advancing the core, continuously'payingeach strip from a supply thereof, onto the core, and continuouslyproviding a relative displacement between the supply and the surface of thecore, as preferably,by advancing the. core horizontally and rotating the supplies of strip around the core axis. At a station between the supply and the core I continuously twist each strip beyond its torsional elastic limit, between upstream and downstream gripping means such, preferably, as pairs of rolls, and at the downstream gripping means I continuously bend the twisted strip toward the core, beyond its elastic limit of bending, thereby imparting a permanent helical form to the strip. Without furtherworking of the strip I wrap it around the core directly from'the downstream gripping means while retaining the twisted form of the strip at all points between the downstream gripping means and the core.

My preferred apparatus for applying armor strip to an elongated core comprises a plurality of supplies of strip and a supply of the core, means for advancing the core from the supply and means rotating the supplies of strip around the axis of the core at a speed having a selected ratio to the speed of advancing of the core. My apparatus also'comprises plurality of support brackets equal to the plurality of supplies of strip and means mounting the bracket radially of the axis of the core and evenly spaced around the core. A support arm is mounted on each of the brackets in a plane passing through the core axis anda pair of heavy rolls are provided foreach support arm with means mounting one pair upstream and one pair downstream while spacing the rolls of each pair a sufficient distance apart for the passage therebetween of the strip but sufficiently close to restrain the strip from turning. The arms are sufficiently removed, radially, from. the core to cause bending of the strips beyond their elastic bending limit on leaving thedownstr'eam of the pairs of rolls, the angle fo the strip being naturally determined by the above recited ratio of speeds and the diameter of the core. Preferably my apparatus comprises means for adjusting the distance between each upstream and downstream pair of rolls and lines them parallel to the core. In a pre ferred embodiment my apparatus comprises a circular plate, means mounting the plate concentric with and in a plane normal to the advance of the core, and means for fixing the bracketsevenly around the plate. Advantagously' my apparatus may comprise a spacer disk mounted downstream of the rolls and defining a plurality of evenly spaced, preferably radial, guide slots for the strips to guide the strips uniformly around the core.

7 BRIEF DESCRIPTION-OF THE DRAWING FlGfl shows the steps of the method of my invention with a side view of a novel apparatus for performing this method.

FIG. 2'shows a chart of the effect of twisting distance and bending angle on helix diameter;

FIG. 3' shows a view through the lines 3-3 of FIG.

FIG. 4 shows a view through the lines 4-4 of FIG. I.

FIG. 5 shows a sideview of anotherembodiment of the bracket and arm assembly of my invention.

FIG. 6 shows a view through the lines 6-6 of FIG. 5-

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIG. 1 the steps of my method are shown as'performed with an apparatus indicated, generally by the numeral I0 for winding 24 copper clad steel strips 11 around a cable core 12. Supplies 13 of the stripon reels 14 are supported for rotation around the core 12 on a conventional stranding machine 16 of the type known as a rigid strander through which the core can pass from a large supply 17 on a reel 18. A hollow mast 20 projects from a front plate 21 of the machine 16 and a large flat disk 22 is mounted around and supported by the mast 20. The disk 22 is 35 inches in diameter since it has been found that this large size is advantageous for separating the twisting means for a large number of armor strips. To mount the disk 22 on the mast 20 it is bolted to a plate on the end of the mast 20. The disk 22 is welded to a hub 23 and 3 gusset plates 24, which, in turn are welded to an alignment ring 26. Bolts 27 through the hub 23 and bolts 28 through the ring 26 adjustably support a tube 19. By loosening the bolts the position of the tube 19 lengthwise of the mast can be adjusted. The disk 22 is pierced by a plurality of pairs of clearance holes 29, 21 each cooperating with holes 32, 33 in a bracket 34 so that 24 of the brackets, equal to the number of strips, can be radially mounted around the disk 22 by means oflock bolts 36. Clearance holes 37, 38 at the tops of the brackets match tapped holes 39, 41 in 24 support arms 42 so that the latter can be mounted'in lines parallel to the core 12.'The arms 42 bear lengthwise grooves 43, 44 for sliding but lockable engagement with plates 45, 46 each rigidly mounting a pair of heavy rolls such as rolls 47, 48 on the plate 46, having a gap 49 between them through which the strip 11 can' pass without excessive friction but small enough to prevent the strip from twisting. A spacer 51 in the form ofa circular disk with 24'deep radial slots 52 wide enough to pass the strips 11 without'obstruction, is mounted at an end 53 of the tubel9. Downstreamof the spacer 51 a smoothing die 54 is. mounted on a standard 56 to guide and supportthe armored cable '57 which is urged forward by a capstan 58 connected through suitable gearing to advance the cable at a fixed ratio to the rotation of the stranding machine 16.

In the illustrated application the rolls 47, 48 on the plate 46 are mounted 6 inches downstream of a pair of rolls 59, 61 similarly mounted on the plate 45. The plates 45,46 are locked on the arm 42 to establish the 6-inch distance by means ofmatching plates 62, 63 and nuts 64 which tighten onto threaded shafts 66 of the rolls 47, 48, 59, 61 and identical rolls mounted similarly around the disk 22. Between the rolls 59, 61 and ,the rolls 47, 48 the strip 11 takes a full twist 67 around its own axis and the twisting of the strip is continued downstream of the rolls 47, 48 in complete twists 68, 69, 71 to the point where it reaches, and wraps around, the core 12. In reaching the core 12 each of the strips passes through one of the slots 52 in the spacer 5] and the spacer is so positioned as to be at a section where the twisting of the strips has turned their long dimension of the section radial to the'core. Within this limitation, the spacer 51 is positioned as far downstream as possible so that is has the maximum effect of distributing the strips evenly around the core. The 6-inch separation of the rolls 59, 61 and 47, 48 was determined .for the strips 11 by a simple experimental procedure to be described hereinafter,- as was the determination to apply a full twist to the strip between the roll pairs. With all the rolls on parallel axes a half-twist or any multiple thereof might be applied to the strip, as desired, and by mounting one .pair of rolls on an oblique claims.

axis fractional twists would be possible. The twist 67 serves to preform the strip into the shape it will have when it is helically applied to the core, and for this purpose the degree of twisting must exceed the elastic twisting limit of the strip so that a permanent residual twist remains, downstream of the rolls 47, 48. This degree of twisting, determining the pitch of the residual twist depends upon both the angle to which the strip is twisted between the pairs of rolls 59, 61 and 47, 48 and the distance between the rolls, both of which can be selected in the apparatus 10. To select an angle of twist, 360 for the illustrated twist 67, the strips are twisted by means of an appropriate hand tool during the stringing up of the apparatus before the leading ends of the strips are initially bound to the core 12.

If the twisted strip 11 were merely pulled straight through the pairs of rolls 59, 61 and 47, 48 on a lead line containing a swivel joint to free it from any untwisting torque, it would emerge downstream with merely a flat twist but no helix. This, indeed, is the technique that was used to prepare the chart of FIG. 2 except that, to obtain a helix the strip was bent around the roll 48, creating an angle off the axis through the rolls corresponding to the angle A of FIG. 1. In FIG. 2 D designates the distance between rolls for a full twist of the strip described in the aforementioned Barone et al. application, the abscissa represents the diameter of the helix that will be assumed by the strips and the ordinate represents the lay length or pitch of this helix. From the chart of FIG. 2 it is evident that, for a given distance between roll pairs, a greater helix diameter results from a sharper bend over the roll 48 (an increased angle A), and that, for a given angle A, a decrease in the distance between roll pairs will decrease the lay length.

In bending around the roll 48 a sharp enough bend must be made so that the elastic limit of the strip in bending is exceeded and a permanent deformationv takes place. For this reason, and also because it must accommodate the twist in the strip, the diameter of the roll 48 must be kept small. In the illustrated apparatus 10 the diameters of the rolls is 1% inches.

In FIGS. 5 and 6 I have shown a modified embodiment of the brackets and arm of my apparatus which provides for adjustment of the radial distance of the arm from the core and for varying the angle A. A modified bracket 72 has a lengthwise slot 73 in its outer extremity which becomes radial on the apparatus. An arm 74 mounting the plates 46 is adjustably locked to the bracket 72 by means of a large headed bolt 76 and nut 77. By tilting the arm 74 to the position shown in phantom in FIG. 5, before tightening the nut, the angle is increased to the angle A. A guide plate 78 has been welded to each of the upstream of the plates 46 to avoid sharp bending of the strip 11 on entering an upstream pair of rolls 79, 81.

l have invented a new and useful apparatus and method of which the foregoing description has been exemplary rather than definitive and for which I desire an award of Letters Patent as defined in the following I claim:

1. A method of helically applying at least one armor strip to an elongated core comprising the steps of:

A. continuously advancing saidcore,

B. continuously paying said strip from a supply thereof, onto said core,

zontal.

D. at a station between said supply and said core continuously twisting said strip beyond its torsional elastic limit between upstream and downstream gripping means, thereby imparting a permanent twist to said strip,

E. at said downstream gripping means, continuously bending said twisted strip toward said core beyond its elastic limit of bending, thereby imparting a permanent helical form of a diameter approximating the diameter of said core to said strip,

F. without further working of said strip, wrapping said strip around said core directly from said downstream gripping means, said strip retaining its twisted form at all points between said downstream gripping means and said core.

2. The method of claim 1 wherein said strip is twisted by pulling it between two pairs of rolls and is bent around one of the rolls of the downstream of said pair, said one roll having a radius small enough for said strip to be bent beyond its elastic limit of bending.

3. The method of claim 1 comprising a plurality in excess of six of said supplies and of said strips being wrapped around said-core. i

4. The method 'of claim 1 wherein said supplies are rotated around the axis of said core.

5.- The method of claim 4 wherein said axis is hori- 6. The method "of claim 3 wherein said supplies are rotated around the axis of said core.

7. An apparatus for applyingarmor strips to an elongated core comprising: A. a plurality of supplies of said core. I v

B. means advancing said core from said supply,

C. means rotating said supplies of strip around the axis of said core at a speed having a selected ratio said strip and a supply of to the speed of advancing of said core,

D. a like plurality of support brackets,

E. means mounting said brackets radially of the axis of said core, evenly spaced around said core,

F. a like plurality of support arms mounted on said brackets in planes passing through said axis,

G. a plurality of pairs of rolls sufficiently heavy to I twist said strip beyond its torsional elastic limit,

H. means mounting one of said pairs at an upstream position and one of said pairs at a downstream position on each of said arms, said means spacing the rolls of each pair a distance sufficiently separated for the passage therebetween of said strips and sufficiently narrow to restrain said strips from turning, said arm being sufficiently removed radially from said core to bend said strip beyond itselastic bending limit on leaving the downstream of said pairs, the angle of said strip being naturally determined by said ratio and the diameter of said core.

8. The apparatus of claim 7 wherein the said upstream and downstream pairs are in a line parallel to said core. I

9. The apparatus of claim 8 comprising means for adjusting the distance between said upstream and downstream pairs.

10. The apparatus 'of claim 7 wherein said bracket mounting means comprises a circular plate, means mounting said plate normal to the advance of said core and concentric therewith, and means for fixing said brackets evenly around said plate. I

11. The apparatus of claim 7 comprising a spacer disk. means mounting said disk downstream of said rolls, said disk defining a plurality of'evenly spaced radial guide slots for said strips whereby said strips are uniformly guided around said core.

12. The apparatus of claim 11 wherein-said guide slots are radial. 

1. A method of helically applying at least one armor strip to an elongated core comprising the steps of: A. continuously advancing said core, B. continuously paying said strip from a supply thereof, onto said core, C. continuously providing a relative angular displacement between said supply and the surface of said core, D. at a station between said supply and said core continuously twisting said strip beyond its torsional elastic limit between upstream and downstream gripping means, thereby imparting a permanent twist to said strip, E. at said downstream gripping means, continuously bending said twisted strip toward said core beyond its elastic limit of bending, thereby imparting a permanent helical form of a diameter approximating the diameter of said core to said strip, F. without further working of said strip, wrapping said strip around said core directly from said downstream gripping means, said strip retaining its twisted form at all points between said downstream gripping means and said core.
 2. The method of claim 1 wherein said strip is twisted by pulling it between two pairs of rolls and is bent around one of the rolls of the downstream of said pair, said one roll having a radius small enough for said strip to be bent beyond its elastic limit of bending.
 3. The method of claim 1 comprising a plurality in excess of six of said supplies and of said strips being wrapped around said core.
 4. The method of claim 1 wherein said supplies are rotated around the axis of said core.
 5. The method of claim 4 wherein said axis is horizontal.
 6. The method of claim 3 wherein said supplies are rotated around the axis of said core.
 7. An apparatus for applying armor strips to an elongated core comprising: A. a plurality of supplies of said strip and a supply of said core, B. means advancing said core from said supply, C. means rotating said supplies of strip around the axis of said core at a speed having a selected ratio to the speed of advancing of said core, D. a like plurality of support brackets, E. means mounting said brackets radially of the axis of said core, evenly spaced around said core, F. a like plurality of support arms mounted on said brackets in planes passing through said axis, G. a plurality of pairs of rolls sufficiently heavy to twist said strip beyond its torsional elastic limit, H. means mounting one of said pairs at an upstream position and one of said pairs at a downstream position on each of said arms, said means spacing the rolls of each pair a distance sufficiently separated for the passage therebetween of said strips and sufficiently narrow to restrain said strips from turning, said arm being sufficiently removed radially from said core to bend said strip beyond its elastic bending limit on leaving the downstream of said pairs, the angle of said strip being naturally determined by said ratio and the diameter of said core.
 8. The apparatus of claim 7 wherein the said upstream and downstream pairs are in a line parallel to said core.
 9. The apparatus of claim 8 comprising means for adjusting the distance between said upstream and downstream pairs.
 10. The apparatus of claim 7 wherein said bracket mounting means comprises a circular plate, means mounting said plate normal to the advance of said core and concentric therewith, and means for fixing said brackets evenly around said plate.
 11. The apparatus of claim 7 comprising a spacer disk, means mounting said disk downstream of said rolls, said disk defining a plurality of evenly spaced radial guide slots for said strips whereby said strips are uniformly guided around said core.
 12. The apparatus of claim 11 wherein said guide slots are radial. 